Study says climate is biofuel foe

Corn flows at an ethanol plant in Garnett, Kan. Researchers from Rice and the University of California at Davis found that a rise in temperatures would cut the ethanol yield 7 percent within 40 years.

A new study suggests demands for water will make it more difficult for the United States to meet current biofuel goals if the climate continues to evolve as predicted by the Intergovernmental Panel on Climate Change.

The study by researchers at Rice University and the University of California at Davis found that a hotter planet would cut the yield of corn grown for ethanol in the United States by 7 percent, while increasing the amount of irrigation needed by 9 percent within 40 years.

The biofuel mandate, set by the Energy Independence and Security Act of 2007, calls for the nation to derive 15 billion gallons per year of ethanol from corn by 2022, to be blended with conventional motor fuels.

The federal mandate is intended to lower emissions from fossil fuels and reduce the nation's dependence on imported oil.

But it has become increasingly controversial, drawing opposition from a variety of forces. At the same time, domestic oil production has soared as new technology allows for oil to be drawn from shale rock formations.

Pedro Alvarez, chairman of Rice University's civil and environmental engineering department, said the realities of an evolving climate may limit compliance with the biofuel mandate.

“Biofuels offer a means to use more renewable energy while decreasing reliance on imported oil, (but) it is important to recognize the trade-offs,” he said. “One important unintended consequence may be the aggravation of water scarcity by increased irrigation in some regions.”

The American Petroleum Institute, an industry trade group, has been a long-time critic of the mandate, arguing that it increases costs for fuel makers and ultimately for consumers.

Environmentalists aren't sold on corn-based ethanol, either, because of concerns that using corn to produce ethanol raises food prices, as well as increasing fertilizer runoff.

But the impact of a changing climate has received less attention. The current paper by the researchers is one of several they have written questioning the mandate.

In 2009, Alvarez and Rice alumna Rosa Dominguez-Faus, now a post-doctoral researcher at the University of California at Davis, calculated it would take 50 gallons of water to grow enough Nebraska corn to produce the amount of ethanol needed to drive 1 mile. In that paper, they suggested the potential consequences to the water supply needed more study.

In the new research, they built computer simulations based on crop data from the nation's top 10 corn-producing states, along with estimates of carbon dioxide and other emissions from the Intergovernmental Panel on Climate Change, an international group established by the United Nations and the World Meteorological Organization to assess the most current scientific research on climate science.

They found that states in the corn belt — Iowa, Illinois, Indiana, Ohio and Missouri — along with Minnesota and Wisconsin, where corn growth is primarily fed by rainfall, would be subject to more intense but less frequent precipitation, especially during the summer. Crops would require as much as 25 percent more irrigation.

Irrigation already is used in South Dakota, Nebraska and Kansas, but the researchers said crop yields would decline even if irrigation continued.

“The projected increases in water intensity due to climate change highlight the need to re-evaluate the corn ethanol elements of the Renewable Fuel Standard,” Dominguez-Faus said in a statement.